From bd57f345ed9dbed1d81683e48199626de2ea9044 Mon Sep 17 00:00:00 2001
From: 3gg <3gg@shellblade.net>
Date: Fri, 27 Jun 2025 10:18:39 -0700
Subject: Restructure project

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 contrib/cgltf-tangents/README.md | 42 ++++++++++++++++++++++++++++++++++++++++
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+# cgltf-tangents
+
+A library to compute missing tangent vectors in glTF models using MikkTSpace.
+
+## Example
+
+```
+// Load the glTF scene and buffers as usual.
+cgltf_result result = cgltf_parse_file(&options, filepath, &data);
+cgltf_load_buffers(&options, data, filepath);
+
+// Compute missing tangents.
+cgltfTangentBuffer* tangent_buffers = 0;
+cgltf_size num_tangent_buffers = 0;
+cgltf_compute_tangents(&options, data, &tangent_buffers, &num_tangent_buffers);
+```
+
+## About
+
+This is a single-header/source library that combines
+[MikkTSpace](https://github.com/mmikk/MikkTSpace) and
+[cgltf](https://github.com/jkuhlmann/cgltf) to compute missing tangent vectors
+for models.
+
+Mesh primitives in glTF may have a normal map but not necessarily tangent
+vectors. An example is the
+[DamagedHelmet](https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/DamagedHelmet/glTF)
+sample. From the
+[spec](https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#meshes):
+
+*"When tangents are not specified, client implementations SHOULD calculate
+tangents using default MikkTSpace algorithms with the specified vertex
+positions, normals, and texture coordinates associated with the normal texture."*
+
+cgltf-tangents takes an input glTF scene and scans it for mesh primitives that
+have a normal map but no tangents. cgltf-tangents then invokes MikkTSpace to
+compute tangents for those mesh primitives and outputs an array of tangent
+buffers. The client can then upload these buffers to GPU memory for rendering.
+
+See `test/` for a complete example.
+
+MikkTSpace is packaged here for convenience. cgltf must be obtained separately.
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